Require Go 1.21 as minimal version of Go

Author: elgopher

.github/workflows/build.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-20.04
     strategy:
       matrix:
-        go: [ "1.20" ]
+        go: [ 1.21 ]
     env:
       DISPLAY: ':99.0'
     steps:

README.md

@@ -39,7 +39,7 @@ Pi is under development. Only limited functionality is provided. API is not stab
 ## How to get started?
 
 1. Install dependencies 
-   * [Go 1.20+](https://go.dev/dl/)
+   * [Go 1.21+](https://go.dev/dl/)
    * If not on Windows, please install additional dependencies for [Linux](docs/install-linux.md) or [macOS](docs/install-macos.md).
 2. Try examples from [examples](examples) directory.
 3. Create a new game using provided [Github template](https://github.com/elgopher/pi-template).

go.mod

@@ -1,6 +1,6 @@
 module github.com/elgopher/pi
 
-go 1.20
+go 1.21
 
 require (
 	github.com/hajimehoshi/ebiten/v2 v2.5.6